Menaquinone, also known as vitamin k2 is produced by bacteria and found in certain animal tissue such as liver. The structure of menaquinone is given in Figure 1. In this figure n indicates the number of unsaturated isoprenoid residues, generally being between 1 and 25.
Fig. 1 Vitamin K2 (menaquinone)

It is known that protein rich products such as meat, fish, cheese, eggs and other dairy products as well as fermented soy-bean contain some menaquinone. Table 1 indicates for some of these products the amounts of MK-4 (n=4) or MK-n (n is greater than 4) for certain food products.
TABLE 1Vit K2 concentrationVit K2 concentrationin μg/100 g or μg/in μg/100 g or μg/Food product100 ml MK-4100 ml MK-nMeat 1–30—Fish0.1–2  0.1–2  Natto— 900–1200Cheese0.5–10 40–80Other dairy0.2–15  0–35Eggs10–25—
L. J Schurgers in Journal of Nutritional & Environmental medicine (1999) 9, 115-122 recommends a significant increase of the daily intake of menaquinone to a level of 45 μg per day. However to achieve this amount it will be necessary to adapt the daily diet and for example to increase the amount of cheese to be eaten to say to at least 100 g of cheese per day. For a great number of consumers however high intakes of products like cheese is not acceptable because it either does not fit in their desired diet (they do not like cheese, or do not take animal proteins) or it may be bad for overall health for example cheese has a high caloric content and a high degree of saturated fatty acids that promote cardiovascular disease).
Another possibility to increase the level of menaquinone in the diet is to increase the intake of a fermented soy product (natto) which typically contains 900-1200 μg per 100 g. Sometimes however the use of natto as a food ingredient is less preferred because it is very difficult to process and often provides a less-desired taste to the food products.
For this reason it has been proposed to add menaquinone as an additive to food products so as to increase the menaquinone intake per day.
Gijsbers, Birgit L M et al, British Journal of Nutrition (1996), 76, 223-229 reported that intake of 5 g butter to which 800 μg MK-4 had been added (equivalent to 16 mg MK-4 per 100 g butter) increased the MK-4 levels in blood serum. Yoshio Suzuki, Nutrition Research, 1997, Vol 17, No 10, pp 1607-1615, suggested with regard to prevention and treatment of HDN (haemorrhagic disease of newborn) to improve the fetal vitamin K nutritional status by including vitamin K as a maternal food supplement. It was taught that MK-4 levels in hen's eggs can be increased to about 130 μg per 100 g egg yolk (50 μg per egg) if hen are fed for 30 days on a menadione enriched diet.
Up till now however it was believed that menaquinone when used as a food additive has to be used at relative high levels say 100,000 μg per 100 g product in order to be effective to promote bone or cardiovascular health. For example in the Chem Abstract of JP 11/127816 a beverage is described which contains 0.1 part menaquinone on 100 parts of product, said menaquinone level corresponding to 100,000 μg per 100 g of product.
The purpose of the present invention is to provide food products with an effective level of menaquinone, said food products being easy to manufacture at a reasonable cost and whereby the level is chosen such that the food product is effective to promote bone health or cardiovascular health.
Surprisingly it has now been discovered that a food product comprising a menaquinone as an additive in a specific amount can be used for promoting the health of human beings, in particular cardiovascular and bone health. Especially it has been found that the amount of menaquinone per serving or per 100 g of product can be kept at a significantly lower level than proposed till now for food products, while still providing the desired health effects.
Accordingly in a first aspect the invention relates to a food product comprising menaquinone at a level of 50 to 5,000 μg per 100 g of product. In a second embodiment the invention relates to a food product comprising menaquinone at a level of 50 to 5,000 μg per serving. If the menaquinone is a MK-n menaquinone, then food products that naturally comprise these levels of menaquinone such as some cheeses and natto are excluded from the scope of the invention.
In another preferred embodiment of the invention the food product is not a highly proteinaceous food product such as meat, fish, dairy product or eggs.